The overall purpose of this project is to study papilledema at the clinical, histologic and ultrastructural levels by comparing the effects of increased intracranial pressure and decreased intraocular tensions in experimental models and comparing the morphologic anatomy in these experimental models to that in humans with papilledema. In this program we have also studied the axoplasmic flow through the normal optic disc of rhesus monkey and the circulatory dynamics of the optic disc with horseradish peroxidase as an ultrastructural tracer.